Pyrazine Based Type-I Sensitizing Assemblies for Photoreduction of Cu(II) in ‘One-Pot Three-Component’ CuAAC Reaction Under Aerial Conditions

Photosensitizing assemblies of pyrazine derivative PDA have been developed which exhibit a high photostability, ‘lighted’ excited state, balanced redox potential, high transportation potential and activate oxygen via type-I pathway only. These PDA assemblies in combination with Cu(II) ions catalyze the CuAAC reaction via in situ reduction of Cu(II) ions without any reducing or stabilizing agent. The present protocol has wide substrate scope with recyclability of the catalytic system up to six catalytic cycles and is applicable to gram-scale synthesis.     

CH activation with an O-donor iridium-methoxo complex

A thermally and air stable O-donor, iridium-methoxo complex is reported that undergoes stoichiometric, intermolecular C-H activation of benzene with co-generation of methanol and the iridium-phenyl complex.     

Synthesis of New Macrocyclic Polyaza Compounds Containing 1-Methylpyrazole

New macrocyclic polyaza compoundscontaining the 1-methylpyrazole moiety are synthesizedin high yield by [2+2]dipodal condensation andreduction. The ring contracted structure of the Schiffbase has been elucidated by NMR. Two of thesemacrocycles form dinuclear complexes with copper andsilver. Macrocyclic Schiff base 5a extracts74.5% silver from aqueous to organic phase.     

Synthesis and binding studies of novel thiacalixpodands and bisthiacalixarenes having O,O″-dialkylated thiacalix[4]arene unit(s) of 1,3-alternate conformation

A series of thiacalixpodands and bisthiacalixarenes with imine units have been prepared by condensation of O,O″-bis(2-aminoethyl)-O′,O?-dipropyl-p-tert-butylthiacalix[4]arene of 1,3-alternate conformation with different aromatic (di)aldehydes. The molecules derived from pyridine-2-carbaldehyde and -2,6-dicarbaldehyde quantitatively extract silver ion from aqueous into organic phase with complete selectivity over other metal ions (Na⁺, K⁺ and Cs⁺) under neutral conditions. The former compound forms a 1:2 (L:M) complex with silver ion as proved by NMR spectroscopy, Job’s plot and X-ray crystallography.     

Diastereoselective synthesis of novel 3-aryloxy/alkoxy-4-benzothiazolylpyrazolyl-β-lactams: Potential synthons for novel aminoacids/nanocopolymers

A fast, efficient, and diastereoselective synthesis of novel 3-oxo-4-benzothiazolylpyrazolyl-β-lactams is described. The reaction between 2-aryloxy/alkoxyacetic acid and novel benzothiazolylpyrazole-substituted imines afforded exclusive formation of trans-β-lactams. The scope of the reaction was investigated by varying different groups on substrates (R¹, R², R³, Z). All the novel compounds were characterized using various spectroscopic techniques such as FT-IR, ¹H NMR, ¹³C NMR, elemental analysis, and mass spectrometry in representative cases. No report has been listed in the literature for the synthesis of these types of β-lactam heterocycles so far.     

Specific heat of SbSI

The temperature dependence of the specific heat of vapor and flux grown single crystal samples of ferroelectric antimony sulfur iodide (SbSI) was measured over a temperature range from 230K to 400K. C_p^E at T_c of the electrical flux and vapor grown samples are 0.078 cal/gmK and 0.076 cal/gmK respectively. ΔS and ΔQ at T_c are evaluated. The samples measured were grown by two different methods[1,2]. Differences are observed between the measurements made on the samples, both in the magnitude of the specific heat and the temperature at which the ferroelectric transition takes place. These differences are caused by the different levels of oxygen impurities in the samples.     

New fourth- and sixth-order classes of iterative methods for solving systems of nonlinear equations and their stability analysis

Numerical Algorithms - In this paper, a two-step class of fourth-order iterative methods for solving systems of nonlinear equations is presented. We further extend the two-step class to establish a...